1. Field of the Invention
The present invention relates to a needle assembly used for introducing a catheter into a blood vessel of a patient.
2. Description of the Related Art
Catheters are used for administration of various medical fluids to patients. To introduce a catheter into a blood vessel of a patient, a needle assembly with a needle on which the catheter is fitted is frequently used. A medical personnel sticks the needle with the catheter into the patient and then extracts the needle alone. Thereby, the catheter is left indwelled in the blood vessel. In the course of this process, the personnel often lets a small quantity of the patient's blood to flow through the hollow needle to determine whether the needle is properly positioned within the blood vessel or not. This practice of using the blood is termed “flashback”.